JP2023061947A - Inkjet ink for tablet and printing method and tablet printer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink suitable for printing on an alkaline tablet, and a method for manufacturing a printed tablet and a tablet printer using the same.

SOLUTION: Ink jet ink for a tablet according to an embodiment contains an edible dye, a resin component containing shellac, propylene glycol, and a solvent containing ethanol and water, wherein a content of the dye in the inkjet ink for the tablet is 0.1 wt.% or more and 10 wt.% or less; a content of the resin in the inkjet ink for the tablet is 0.5 wt.% or more and 10 wt.% or less; a content of the ethanol in the inkjet ink for the tablet is 20 wt.% or more and 40 wt.% or less; and a content of the water in the inkjet ink for the tablet is 30 wt.% or more and 48 wt.% or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD Embodiments of the present invention relate to an inkjet ink for tablets, a printing method using the same, and a tablet printing apparatus.

By printing identification information such as characters and symbols on tablets, it is possible to improve the identification of tablets, prevent dispensing errors by dispensing personnel, prevent users from accidentally swallowing tablets, and the like.

As a method of printing on tablets, there is ink-jet printing. According to inkjet printing, tablets can be printed in a non-contact manner, so that tablets with a high risk of disintegration such as OD tablets (orally disintegrating tablets) can be suitably printed. be able to.

In such inkjet printing, an ink containing a dye (dye ink) is sometimes used. With dye ink, printed characters and the like are more likely to develop a darker color than with ink containing pigment, and the visibility of identification information is improved. In addition, since the pigment is dispersed in the solvent, the ink containing the pigment has a poor ejection property from the nozzle of the inkjet head, which may cause ejection failure and printing failure. On the other hand, in dye ink, since the dye is dissolved in the solvent, it is easy to ensure ejection performance from the nozzles of the inkjet head, and printing defects can be suppressed.

JP 2011-236279 A

An object of the present invention is to provide an ink suitable for printing on alkaline tablets, a method for producing printed tablets using the same, and a tablet printing apparatus.

An inkjet ink for tablets according to an embodiment of the present invention is an inkjet ink for tablets containing an edible dye, a resin component containing shellac, propylene glycol, and a solvent containing ethanol and water, The content of the dye in the inkjet ink for tablets is 0.1 weight percent or more and 10 weight percent or less, the content of the resin in the inkjet ink for tablets is 0.5 weight percent or more and 10 weight percent or less, The content of ethanol in the inkjet ink is 20% by weight or more and 40% by weight or less, and the content of water in the inkjet ink for tablets is 30% by weight or more and 48% by weight or less.

In a printing method according to an embodiment of the present invention, the inkjet ink for tablets described above is discharged from an inkjet head to adhere the inkjet ink to the tablet for printing.

A tablet printing apparatus according to an embodiment of the present invention includes:
a conveying device for conveying tablets;
a print head that performs printing by ejecting ink from nozzles on the tablet transported by the transport device;
The print head is characterized by ejecting the ink described above.

In inkjet printing, ink filled in an inkjet head is ejected from an opening in a nozzle at the tip of the inkjet head. If the ink dries and adheres in or around the opening of the nozzle, and the shape of the opening is deformed or clogged, ejection failure occurs. In addition, if the viscosity of the ink is high, the ink cannot be ejected normally from the nozzles, resulting in ejection failure. Ink droplets ejected from the nozzles of the inkjet head land on the surface of the tablet to be printed, and the printed dots formed by these droplets are combined to create characters and symbols in stippled style. etc. will be printed. At this time, if there is an ejection failure, printing dots may not be formed in a pattern for characters or symbols, and printing may appear blurred or the desired characters or symbols may not be seen, resulting in printing failure.

Furthermore, if the ink that has landed on the surface of the tablet does not dry quickly, the ink may peel off during transportation after printing, or may adhere to other tablets or transportation devices and stain them. Therefore, the inkjet ink used for tablet printing must have both ejection properties from nozzles and drying properties after printing.

Tablets contain alkaline raw materials or are coated with alkaline ingredients, and there are tablets whose surface (at least the part to be printed) exhibits alkalinity (hereinafter simply referred to as "alkaline tablet"). . It has been found that when dye ink is used for printing on alkaline tablets, the printed letters and the like may change color or bleed over time, depending on the dye.

In particular, for blue ink, for example, alkaline tablets are printed with ink containing Food Blue No. 1 (Brilliant Blue FCF), which is generally and widely used as a blue dye, and stored in an environment with a temperature of 40 degrees and a humidity of 75% RH. Then, the printed identification information turns light purple in one to two days, and bleeding occurs. In other words, the color changes to a color different from the color immediately after printing or the desired color (predetermined color). put away. In addition, when characters are printed, the characters become unclear due to the bleeding that occurs, which reduces the distinguishability of tablets.

Therefore, the inventors of the present application have invented an ink capable of suitably printing identification information on alkaline tablets even when Food Blue No. 1 is used as a coloring matter.

[ink]
The ink according to this embodiment will be described. The ink of this embodiment is an inkjet ink, and is a blue ink particularly suitable for printing on alkaline tablets. At least Food Blue No. 1 is included as a pigment, and at least shellac is included as a resin. In addition, emulsifiers, flavoring agents, preservatives and the like may be blended as necessary. In preparing the ink, it is preferable to use edible compositions such as those approved by the Japanese Pharmacopoeia and the Food Additives Standards as each composition.

(pigment)
The ink of the present embodiment contains at least Food Blue No. 1 (Brilliant Blue FCF) as a pigment. Moreover, it is more preferable to contain gardenia blue pigment together with Food Blue No. 1.

The ink of the present embodiment can be further mixed with other pigments in addition to Food Blue No. 1 and gardenia blue pigments to obtain a desired color including blue or bluish. As other pigments, one or more kinds can be selected from conventionally known synthetic food pigments and natural food pigments. Note that the bluish color is a color that includes blue as a color component, such as green or purple.

Synthetic food colorings include, for example, tar colorings, natural coloring matter derivatives, natural synthetic colorings, and titanium dioxide. Tar colorings include Food Red No. 2, Food Red No. 3, Food Red No. 40, Food Red Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow No. 4, Food Yellow No. 5, Food Blue No. 2, Food Red No. 2 Aluminum Lake, Food Red No. 3 Aluminum Lake, Food Red No. 40 No. 4 aluminum lake, No. 4 food yellow aluminum lake, No. 5 food aluminum lake, No. 2 food blue aluminum lake, etc. Natural pigment derivatives such as copper chlorophyll, copper chlorophyllin sodium, norbixin potassium etc. Natural synthetic pigments , β-carotene, riboflavin and the like.

Examples of natural edible pigments include charcoal powder pigments, anthocyanin pigments, carotenoid pigments, quinone pigments, flavonoid pigments, betaine pigments, monascus pigments, and other pigments derived from natural products. Anthocyanin pigments include red radish pigment, red cabbage pigment, red rice pigment, elderberry pigment, cowberry pigment, gooseberry pigment, cranberry pigment, salmonberry pigment, perilla pigment, swim blueberry pigment, strawberry pigment, and dark sweet cherry pigment. , cherry pigment, hibiscus pigment, huckleberry pigment, grape juice pigment, grape skin pigment, black currant pigment, blackberry pigment, blueberry pigment, plum pigment, whiteberry pigment, boysenberry pigment, mulberry pigment, purple sweet potato pigment, purple purple Corn pigments, purple yam pigments, raspberry pigments, red currant pigments, loganberry pigments, and other anthocyanin pigments. Examples of carotenoid pigments include annatto pigments, gardenia yellow pigments, and other carotenoid pigments. Examples of quinone dyes include cochineal dyes, chikon dyes, lac dyes, and other quinone dyes. Examples of flavonoid pigments include safflower yellow pigment, sorghum pigment, onion pigment, and other flavonoid pigments. Betaine pigments include beet red pigments. Examples of monascus pigments include monascus pigments and monascus yellow pigments. Other pigments derived from natural products include turmeric pigments, gardenia red pigments, and spirulina blue pigments.

The pigment content is preferably 0.1 to 10 weight percent, more preferably 0.5 to 8 weight percent, relative to the total ink composition. If the content of the pigment is less than 0.1% by weight, the printed color becomes light and the visibility deteriorates. On the other hand, if the amount is more than 10% by weight, the viscosity of the ink increases and the ink cannot be ejected normally, resulting in poor printing.

(resin)
By blending the resin component into the ink, the adhesion of the ink to the tablet is improved, and after being printed on the tablet, it dries to form a film, so that abrasion resistance can be obtained. Shellac is used as the resin in the ink of the present embodiment. Shellac is a resin obtained by purifying a resinous substance secreted by lac scale insects, and is a mixture of a plurality of resin acid esters, waxes, pigments, and the like. For blending in the ink, it is preferable to use white shellac obtained by bleaching shellac or purified shellac treated to remove pigments and waxes. In addition, by adding shellac to the ink, the viscosity of the ink can be increased, and the viscosity can be adjusted to be suitable for ejection from nozzles using an inkjet head.

The content of shellac is preferably 0.5 to 10 weight percent, more preferably 1 to 8 weight percent, relative to the total ink composition. If the shellac content is less than 0.5% by weight, printed identification information will be lost in 1 to 2 days when printed on an alkaline tablet and stored in an environment with a temperature of 40 degrees and a humidity of 75% RH. The color changes to pale purple and bleeding occurs. On the other hand, if the amount is more than 10% by weight, the viscosity of the ink increases and the ink cannot be ejected normally, resulting in poor printing.

(pH adjuster)
Shellac is known to dissolve not only in alcohols but also in alkaline aqueous solutions, and by making the ink alkaline, shellac can be maintained in a dissolved state without precipitating out. As the pH adjuster, one approved as a food additive is preferred. In order to obtain water resistance after the ink containing shellac is printed, it is preferably a component that volatilizes when the ink dries. For example, ammonium carbonate or ammonium hydrogencarbonate can be used. The pH of the ink is preferably 6.5-10.

(ethanol)
Ethanol is preferably naturally brewed fermented ethyl alcohol, sugarcane alcohol, or the like. The content of ethanol is preferably 5 to 60 weight percent, more preferably 10 to 40 weight percent, relative to the total ink composition. If the ethanol content is less than 5% by weight, the ink has poor drying properties. For example, it takes 3 seconds or more to dry after printing. It adheres to equipment and makes it dirty. In addition, the surface tension of the ink increases, making it easier for the printed ink to be repelled by the surface of the tablet. That is, since it does not wet and spread on the surface of the tablet, it does not dry easily, and since the contact area with the surface of the tablet is small, the adhesive force becomes weak, and even after 24 hours, for example, it comes off when rubbed. On the other hand, if the amount is more than 60% by weight, the ink dries and adheres in or around the openings of the inkjet nozzles, clogging the openings and causing ejection failure or deviation of the flying direction of the ejected ink. , the print is defective.

(Water-soluble high boiling point organic solvent)
The water-soluble high boiling point organic solvent is used for the purpose of preventing drying of the nozzles of the inkjet head. As the water-soluble high boiling point organic solvent, for example, one or more can be selected from propylene glycol and glycerin. The content of the water-soluble high boiling point organic solvent is preferably 1 to 60 weight percent, more preferably 2 to 55 weight percent, relative to the entire ink composition. If the water-soluble high-boiling organic solvent is less than 1% by weight, the ink in the ink-jet nozzle dries, resulting in poor printing. On the other hand, if the amount is more than 60% by weight, the viscosity of the ink increases and the ink cannot be ejected normally, resulting in poor printing.

(emulsifier)
As the emulsifier, for example, one or two or more water-soluble emulsifiers can be selected from lecithin, glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. An emulsifier does not necessarily have to be blended, but when blended, the content of the emulsifier is preferably 0.01 to 5% by weight, more preferably 0.1 to 2% by weight, based on the total ink composition. . If the content is less than 0.01% by weight, the surface tension of the ink increases, and an appropriate meniscus state does not occur at the nozzle opening. A printing error occurs when the ink does not land at a predetermined position. On the other hand, if the content is more than 5% by weight, the viscosity of the ink increases and deposits are formed over time, which may cause clogging of the nozzles, resulting in poor printing.

(manufacture of ink)
Next, the present embodiment will be specifically described with examples and comparative examples shown in Table 1. However, these examples are examples, and the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Examples 1 and 2 were prepared using the respective compositions shown in Table 1 at the mixing ratios shown in Table 1. All of the compounding ratios shown in Table 1 are indicated by weight percent. Examples 1 to 3 are inks containing Food Blue No. 1 and shellac. Comparative Example 1 is an ink containing Food Blue No. 1 as a pigment (no shellac), and Comparative Example 2 is an ink containing a gardenia blue pigment as a pigment.

Since Comparative Example 1 does not contain shellac, the proportion of propylene glycol was increased to adjust the viscosity to be suitable for printing with an inkjet head. In Comparative Example 2, in order to dissolve the gardenia blue pigment, the proportion of purified water is higher and the proportion of ethanol is lower than those of other Examples and Comparative Examples.

The operation of preparation is as follows. First, all except the dyes shown in Table 1 were heated to 50° C. and stirred to dissolve. After each component was dissolved, the dyes shown in Table 1 were mixed and further stirred at 50° C. for 1 hour. After that, the mixture was allowed to stand for 1 hour, cooled to room temperature, and then filtered to prepare an ink.

The dyes to be mixed may be in the form of a powder, a solution dissolved in a liquid such as water, or a paste in which the dyes are dispersed. Finally, it is sufficient that the dyes are evenly dissolved or mixed.

(Evaluation of ink)
The prepared inks of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for ejection properties from nozzles using an inkjet head. Furthermore, characters were printed on the tablet to be printed, and the light resistance of the print and the stability of the print over time were evaluated (each evaluation method will be described later). In each evaluation, an OD tablet containing magnesium oxide as a main component, which is a type of alkaline tablet, was used as a printing target. The results are shown in Table 1.

<Evaluation of ejectability from nozzle>
The jettability from the nozzle was evaluated by filling the ink jet head with the ink, leaving it for 15 minutes, and performing a printing test to visually confirm the presence or absence of printing defects.
◯: Each print dot is formed at a predetermined position.
x: Missing print dots, or (and) each print dot does not land on a predetermined position.

<Evaluation of light resistance of printing>
After printing on the tablets, the tablets were exposed to light at 1000 lux for 50 days in an unpackaged state, and the presence or absence of fading of the printing was visually confirmed.
◯: No discoloration was observed in the print.
x: Print faded.

<Evaluation of printing stability over time>
To check the stability of printing over time, the printed tablets were stored in an environment of 40°C and 75% RH for 2 weeks, and compared with immediately after printing, the presence or absence of bleeding of characters and the presence or absence of color change were visually confirmed. bottom.
O: No blurring and no discoloration.
Δ: Slightly discolored to a color different from the desired color. Or (/and) bleeding was observed to the extent that there was no problem in visually recognizing the print.
x: Discolored to a color different from the desired color. OR (/AND) the print is blurred and difficult to read.

(result)
As can be seen from the experimental results of Examples 1 to 3 shown in Table 1, the ink containing Food Blue No. 1 as the pigment and shellac as the resin exhibits excellent light resistance when used for printing on alkaline tablets. And the ink was excellent in moisture resistance. Furthermore, the ink containing the gardenia blue pigment in addition to Food Blue No. 1 as the pigment was particularly good. The results will be described in more detail below.

<Example 1>
The ink of Example 1 contains Food Blue No. 1 as the pigment and shellac as the resin. When the inkjet head was filled with the ink of Example 1 and printing was performed, each printed dot was formed at a predetermined position. In the light fastness evaluation, the print printed on the alkaline tablet did not change in color immediately after printing. In the evaluation of stability over time, the blue color slightly faded and slight bleeding was observed, but there was no problem with visual recognition.

<Example 2>
The ink of Example 2 contains a gardenia blue pigment in addition to Food Blue No. 1 as a pigment, and shellac as a resin. When the inkjet head was filled with the ink of Example 2 and printing was performed, each printed dot was formed at a predetermined position. In the light fastness evaluation, the print printed on the alkaline tablet did not change in color immediately after printing. Also in the evaluation of stability over time, no discoloration or bleeding over time was observed, and the print could be read satisfactorily.

<Example 3>
Similarly to Example 2, the ink of Example 3 also contains a gardenia blue pigment in addition to Food Blue No. 1 as a pigment. When the inkjet head was filled with the ink of Example 3 and printing was performed, each printed dot was formed at a predetermined position. In the light fastness evaluation, the print printed on the alkaline tablet did not change in color immediately after printing. Also in the evaluation of stability over time, no discoloration or bleeding over time was observed, and the print could be read satisfactorily.

<Comparative Example 1>
The ink of Comparative Example 1 contains Food Blue No. 1 as a pigment and does not contain a resin component. When the inkjet head was filled with the ink of Comparative Example 1 and printing was performed, each printed dot was formed at a predetermined position. In the light fastness evaluation, the print printed on the alkaline tablet did not change in color immediately after printing. However, in the evaluation of stability over time, the print turned light purple in about 1 to 2 days. Furthermore, bleeding of the print also occurred, making it difficult to read the print.

<Comparative Example 2>
The ink of Comparative Example 2 contains a gardenia blue pigment as a pigment and does not contain a resin component. Natural dyes such as gardenia dyes must be blended in large amounts in order to obtain sufficient print density. In the ink of Comparative Example 1, as a result of blending a sufficient amount of gardenia pigment for visually recognizing the print, the viscosity of the ink increased and the ejection property from the nozzle deteriorated. It should be noted that the composition shown in Comparative Example 2 also has a lower blue density than that of Example 1. In the evaluation of light fastness, the print was faded and almost disappeared. In the stability evaluation over time, neither bleeding nor discoloration of the print was observed.

(summary)
From the results described above, when printing is performed by an inkjet method, the ink containing food blue No. 1 and shellac stabilizes ejection from nozzles and can suppress the occurrence of printing defects. Furthermore, this ink has high light resistance and long-term stability, and can suppress discoloration of printed identification information. In addition, bleeding in printing can be suppressed. Therefore, after printing, the identification information can be easily recognized even after the tablet is stored, and dispensing errors and accidental ingestion can be prevented.

Inks containing shellac were also superior in light resistance and stability over time compared to inks containing no resin component. This is because by blending shellac, the printed ink dries and forms a film on the tablet, making the food blue No. 1 pigment less susceptible to the decomposition of alkaline tablets due to alkali. In addition, since shellac is a resin having an acid, it is thought that the neutralization action works with the alkaline tablet to reduce the influence of alkali on the pigment. Food Blue No. 1 is generally widely used and has excellent color development, but it is not suitable for use in printing on alkaline tablets due to its low stability over time. On the other hand, by blending shellac, it became possible to apply Food Blue No. 1 to the printing of alkaline tablets.

Conventionally, in inkjet inks for printing on tablets, many inks containing shellac have a high ethanol content (for example, about 60% by weight of the total ink composition). ). A high ethanol content causes printing defects as described above. Utilizing the fact that shellac dissolves in an alkaline aqueous solution, if the solvent of the ink is adjusted to be alkaline using, for example, the above-mentioned pH adjuster, an ink in which shellac is dissolved can be prepared even if the ethanol content is suppressed. can be done.

Furthermore, in addition to Food Blue No. 1, it is more preferable to add a gardenia blue pigment as a pigment. By blending both the Food Blue No. 1 and the gardenia blue pigment, the stability of the ink over time can be further enhanced as compared with the case where the pigment is Food Blue No. 1 alone. The results of Comparative Example 2 show that the ink containing the gardenia blue pigment has excellent stability over time. In other words, in addition to food blue No. 1, it is thought that the addition of the gardenia blue pigment supplements the stability over time.

[Tablet printing equipment]
A tablet printing machine can be used to print the identifying information on the tablets. The tablet printing device has a transport device and an inkjet print head. The conveying device is, for example, a suction conveying device that conveys tablets while sucking and holding them. The print head is arranged to face the transport surface of the transport device, and ejects ink from nozzles toward tablets passing below the print head to print identification information on the tablets. The printing head of this tablet printing apparatus is supplied with an ink containing at least Food Blue No. 1 and shellac described above, and printing is performed on the conveyed alkaline tablets to give a blue or bluish color to the alkaline tablets. can be printed with color identification information including

[Other embodiments]
Additives such as flavoring agents, preservatives (bacteriostatic agents), antifoaming agents, and surfactants may be added to the ink, if necessary. Of course, if the object to be printed is medicine, food, or the like, edible items may be selected. In addition, pre-treatment such as heating and post-treatment can be performed when mixing the respective ink compositions.

For stirring in preparation of the ink, generally used stirrers such as magnetic stirrers and propeller stirrers can be used.

The ink may also contain so-called pigments such as pigments at the end of vegetable charcoal, titanium dioxide, and aluminum lake. In the preparation of pigment-containing ink, it is necessary to disperse the pigment. This dispersing treatment is not particularly limited as long as it is a commonly used dispersing machine. Specific examples include ball mills, roll mills, sand mills, bead mills, and the like.

A method for filtering the ink is not particularly limited, and centrifugal filtration, filter filtration, or the like can be employed.

The above-mentioned tablets can include tablets used for medicine, eating and drinking, cleaning, industrial use, or aromatic use, as long as at least the part to be printed is alkaline. Tablets include, in addition to the above-mentioned uncoated tablets and film-coated tablets, sugar-coated tablets, enteric-coated tablets, gelatin-coated tablets, multilayer tablets, and dry-coated tablets. Tablets can also include capsules of various types, such as hard capsules and soft capsules. Further, the shape of the tablet includes various shapes such as disk-shaped, lens-shaped, triangular, and elliptical. Also, when the tablet to be printed is for medicine or eating and drinking, it is preferable that the composition of the ink used is edible. .

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

Claims (9)

An inkjet ink for tablets containing an edible dye, a resin component containing shellac, propylene glycol, and a solvent containing ethanol and water,
a content of the dye in the inkjet ink for tablets is 0.1% by weight or more and 10% by weight or less;
a content of the resin in the inkjet ink for tablets is 0.5% by weight or more and 10% by weight or less;
a content of ethanol in the inkjet ink for tablets is 20% by weight or more and 40% by weight or less;
An inkjet ink for tablets, wherein the content of water in the inkjet ink for tablets is 30% by weight or more and 48% by weight or less. The inkjet ink for tablets according to claim 1, wherein the total content of ethanol and water in the inkjet ink for tablets is 60 weight percent or more and 70 weight percent or less. 3. The inkjet ink for tablets according to claim 1, wherein the dye is a tar-based dye. 3. The inkjet ink for tablets according to claim 1, wherein the tablets are tablets containing magnesium oxide as a main component. 4. The inkjet ink for tablets according to claim 3, wherein the tablets are tablets containing magnesium oxide as a main ingredient. 3. A method of printing by ejecting the inkjet ink for tablets according to claim 1 or 2 from an inkjet head to adhere the inkjet ink to a tablet. 4. A method of printing by ejecting the ink-jet ink for tablets according to claim 3 from an ink-jet head to adhere the ink-jet ink to a tablet. a conveying device for conveying tablets;
a print head that performs printing by ejecting ink from nozzles on the tablet transported by the transport device;
A tablet printing apparatus, wherein the print head ejects the ink according to claim 1 or 2. a conveying device for conveying tablets;
a print head that performs printing by ejecting ink from nozzles on the tablet transported by the transport device;
A tablet printing apparatus, wherein the print head ejects the ink according to claim 3 .